Department of Pathology EAHP2016-BMWS-294 Brian Bockelman, M.D. Jozef Malysz, M.D. Rina Kansal, MD. Michael G. Bayerl, M.D. Department of Pathology Penn State Hershey Medical Center / Pennsylvania State College of Medicine Hershey, PA, USA

Clinical History A 75 year-old man presented to our institution due to a motor vehicle accident (MVA). Two years prior, he had been diagnosed with indolent systemic mastocytosis(SM). During evaluation for his MVA, he was noted to have a macular, erythematous rash over his entire body and palpable hepatosplenomegaly (HSM). Imaging studies confirmed HSM and further identified portal venous hypertension and retroperitoneal lymphadenopathy. Biopsies of liver and lymph nodes showed involvement by SM. At this time he was diagnosed with aggressive SM. Three years later, he developed progressive thrombocytopenia. CBC showed WBC 4.33 x 10^9/L, Hb 88 g/L, HCT 27.0%, RBC 3.00 10^12/L, , MCV 90.0 fL, RDW 16.4%, MCHC 32.6, MCH 29.3, PLT 13 x 10^9/L. Review of blood film confirmed cytopenias with no leukoerythroblastosis, dacrocytosis or dysplastic morphology. A bone marrow evaluation yielded a “dry tap” with only paucicellular touch preparations and a trephine core biopsy.

Bone Marrow Touch Preparation

Mast cell infiltrate and osteosclerosis Haematopoietic marrow

Haematopoietic Bone Marrow

Mast cell infiltrate and osteosclerosis

Giemsa stain

CD117

Clinical Course Two years later he presented with confusion, abdominal pain and vomiting. A CBC showed: WBC 107.5 x 10^9/L, Hb 95 g/L, HCT 30.6%, RBC 3.08 10^12/L, , MCV 99.4 fL, RDW 18.0%, MCHC 31.0, MCH 30.8, PLT 72 x 10^9/L . A 500 cell leukocyte differential showed: 21.2% blast equivalents (blasts + monoblasts + promonocytes), 0.2% promyelocytes, 0.6% neutrophilic myelocytes, 0.2% neutrophilic metamyelocytes, 50.0% band and segmented neutrophils, 25.0% monocytes, 0.2% eosinophils, 0.0 % basophils and 1.6% lymphocytes. The patient deferred bone marrow examination and chose palliative care and expired within days. This was 7 years after his initial diagnosis of indolent SM

Peripheral blood smear 7 years after initial diagnosis

Proposed Diagnosis: Indolent systemic mastocytosis progressing to aggressive systemic mastocytosis with terminal development of acute myeloid leukemia.